This invention relates to a stabilizer for a vehicle, which comprises a torsion section coupled to a vehicle frame, curved sections each integrally extending from each end of said torsion section and arm sections each integrally extending from each curved section and having a free end coupled to a wheel suspension.
Stabilizers of this sort have hitherto been used for the purpose of improving the feel of riding and stability of vehicles such as automobiles by improving the tilting of the vehicle caused at the time of turning due to centrifugal forces and unbalance of the road holding force on the opposite side wheels that is caused at such time. Usually, the stabilizer is constructed of a single elongate metal rod or pipe, which has a torsion section of uniform sectional dimensions and profile, curved sections integrally extending from the opposite ends of the torsion section and defining an obtuse angle and arm sections extending from the respective curved sections. The torsion section is coupled to the frame of the automobile or the like via mounting members such that it extends in the lateral direction, while the arm sections are coupled to the opposite sides of a wheel suspension via coupling sections provided at their free ends. Mounted in this way, the stabilizer acts to suppress the outward tilting of the vehicle and also the floating of the inner wheels at the time of turning of the vehicle.
Since this kind of stabilizer is formed by bending a single piece of material as mentioned above, a hot bending process is adopted, and the system is subsequently subjected to oil hardening or like heat treatment. However, since the eventual stabilizer is immersed in an oil trough without restricting it at all in the heat treatment step, it is liable to be thermally deformed. Such thermal deformation has to be corrected after the oil hardening treatment. Such correction is quite difficult. Besides, at the time of the correction, flows are likely to be caused to the product by the correction mold, thus spoiling the performance of the product.
After investigations conducted by the inventors concerning the load stress produced in the stabilizer, it has been proved that the maximum stress is produced in the curved section while the other sections are subject to bending stress or shearing stress based upon torsional forces that are low compared to the stress in the bending section, thus indicating that it is unnecessary to subject the entire eventual stabilizer to a heat treatment. The present invention is based upon this fact and provides a stabilizer, which can be manufactured economically without lowering its performance as a whole.
The invention is based upon the results of the investigations mentioned above, and its primary object is to provide a stabilizer for a vehicle at a low cost by imparting various parts of the stabilizer with adequate mechanical strengths.